| Electronics > Repair |
| Hantek DSO5102P oscilloscope PSU repair |
| << < (4/5) > >> |
| snoop33:
[Agree to the common choke and noise suppression] Yes I can confirm that diode is in parallel as wasedadoc states and agree with the reasoning. I hope OP doesn't try 1.8ohm resistors before reading that they are 15k, that isn't going to end well at 110+ volts. |
| TDogg:
If anyone is still interested in this topic, to fix the power supply to stop the problems reported here replace the 100uF 400V capacitor (C6) on the DC side of the mains rectifier BD1. It is dry and if you (very carefully) measure the voltage on the DC side before replacing the capacitor you will only get around 200VDC with 100VAC ripple!! |
| Mangy_Dog:
Hi sorry to necropost but my scopes psu just exploded.... First saw the fuse had blown then turned the pcb over and saw the three resistors R14 blew... This is one of the few posts I've seen talking about repairing this PSU... Sooo wanted to drop this question in... What would cause this failure? The caps still look solid and not expanded or leaked. I can fix these resistors fuse but, I might only be repairing the symptoms not the cause. Can anyone confirm the values of the resistors. From the photos at the OPs post show I think 125 1200000R? But its a little pixelated so not sure. Any ideas what made it go pop? |
| pcprogrammer:
For the resistors 1R5 is more likely. Burning up a resistor like these requires energy and with the resulting resistance still being 400k with 3 1.2M in parallel you need a high voltage to get that energy. But it is possible though on the primary rectified side. For this to happen the switching MOSFET driving the transformer can be shorted out. Can happen due to overheating. Best to check the scope circuit first to see if there is a short on it somewhere due to a failed capacitor or some other component. With a proper lab power supply you might be able to power up the scope to see if it still works and check the current draw. If it is al good, then work your way back to the power supply of the scope itself. |
| Mangy_Dog:
Sadly I only had this scope. I have a fairly budget lab :) I do have a bench supply but its currently wired up with a work project so its kinda awkward to swap things around. I might have to put this onto a possible repair sometime later pile. I did wonder if it was 1R5 but it was hard to tell. I have the V1.1 PSU. out of interest is there a schematic for this? It does look like from a couple of other posts, these same resistors releasing the smoke... So I suspect its a design fault. I will look deeper into the unit and check the rest of the PCB to see if anything else has gone... Sadly it happened over night while I left it running in trigger mode hoping to capture an irregular fault were having with a work project. So maybe something did heat up over the long period and just went pop... Again design fault :p |
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